Radiographic markers for measuring tibial rotation based on CT-reconstructed radiographs: an accuracy and feasibility study
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Malreduction in the axial plane (malrotation) following tibial fracture surgery is often undiagnosed. A few clinical and radiographic methods have been proposed for measuring tibial rotation intraoperatively, yet have failed to match the accuracy of computed tomography (CT). The aim of this study was to develop radiographic tools for future intraoperative assessment of the tibial shaft rotation profile.
The setting was a laboratory computerized analysis. Twenty lower limb CT scans were used to construct a three-dimensional (3D) model using AMIRA© software. A virtual 3D cylinder was implanted in the posterior condylar line and in the transmalleolar axis. The 3D models were used to simulate four standard knee and ankle plain radiographs. On each radiograph, four landmarks were depicted by two observers and their relation with the cylinder was measured and analyzed for accuracy and reproducibility. A cadaveric lower leg was implanted with two Kirschner wires. A CT scan was performed in addition to 2D fluoroscopy. The simulated radiographs and the fluoroscopy were compared for accuracy.
Measurement of the landmarks showed reliability in most of the knee anteroposterior and ankle mortise radiographs (coefficients of variation < 0.01 and = 0.01) respectively. Cadaveric measurement of the landmarks using real fluoroscopy and simulated radiographs were similar.
To date, no reliable and common methods have been reported for the evaluation of tibial axial rotation. We propose a model in which simple radiographic landmarks can be used to calculate a 3D coordinate system that accurately assesses the axial rotation angle of the tibial shaft.
KeywordsTibial torsion Tibial fractures Malrotation
Compliance with ethical standards
Conflicts of interest statement
The corresponding authors state on behalf of all other authors that none of the authors has a potential conflict of interests, received any grants or fees concerning any part of this study.
The authors have used only anonymous radiographic data without disclosures of any patients’ data. The ethical board of the institution had waived the need for formal IRB approval or patients’ consent to conduct this study.
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